1. Field of the Invention
The present invention relates to resource management technology, and more particularly, to a method for implementing cross-domain resource management.
2. Background of the Invention
With the expansion of the lnternet, various network services as well as advanced multimedia systems are emerging. As being sensitive to some network characters such as transmission delay and time delay jittering, real time services will be greatly affected when there are services of high burstness transferred on the network, such as services based on File Transport Protocol (FTP) or Hypertext Transfer Protocol (HTTP). In addition, since multimedia services usually occupy large bandwidth, the key services of which the quality should be ensured actually cannot be transmitted reliably in the existing network. Therefore various technologies of Quality of Services (QoS) emerge to guarantee the reliable transmission of key services. Internet Engineering Task Force (IETF) has provided a lot of service models and mechanisms to satisfy the needs of QoS. The model currently ratified in this field includes an Integrated Service (Int-Serv) model employed in the access to or at the edge of a network, and a Differentiated Service (Diff-Serv) model used in the core of a network.
The Diff-Serv model safeguards the QoS by way of setting priorities. Though the model has a character of high efficiency in line utilization, its specific effect cannot be forecast. Therefore, for the Diff-Serv model of a backbone network, an independent bearer control layer is introduced, and a special Diff-Serv QoS signaling mechanism is set up. Besides, a resource management layer is established specially for networks based on the Diff-Serv model to manage the topology resources of the networks. This method of resource management based on the Diff-Serv model is so called a Diff-Serv model with an independent bearer control layer. FIG. 1 is a map of a Diff-Serv model with an independent bearer control layer. As shown in FIG. 1, in this model, a bearer control layer 102 is set up between a bearer network 103 and a service control layer 101. A Call Agent (CA) in the service control layer 101 is a server, e.g., a soft switching device which can implement soft switching functions etc. In the bearer control layer 102, there is one or more bearer network resource managers responsible for configuring management rules and network topology, distributing resources for service bandwidth applications of users, controlling and managing such information transferred via signaling between various bearer network resource managers as requests and results of users' service bandwidth applications, routes and paths assigned for service applications, e.g., controlling and managing the communications between bearer network resource manager 1, bearer network resource manager 2 and bearer network resource manager 3. In bearer network 103, each bearer network resource manager is in charge of a certain area of the bearer network which is called an administration domain of the corresponding bearer network resource manager, such as administration domain 105 of bearer network resource manager 1, administration domain 106 of bearer network resource manager 2, and administration domain 107 of bearer network resource manager 3. Bearer network 103 includes Edge Routers (ER) e.g., ER 1 and ER 2, Border Routers (BR) e.g. BR 1, BR 2, BR 3, and BR 4, and Core Routers, e.g., Core Router 104. All the ERs, BRs, and Core Routers belong to the bearer network and can be called Connection Node (CN).
In a Diff-Serv model with an independent bearer control layer, each bearer network resource manager has been configured with management rules and network topology so that it is able to distribute service resources for users' service bandwidth applications. During the processing of a user's service bandwidth application by the bearer control layer, the bearer network resource manager first determines the current route of the user's service, and informs an ER that the service traffic should be transmitted along the determined route. At present, the process of transmitting the user's service traffic on the bearer network along the route determined by the bearer control layer is usually implemented by using the Multi-Protocol Label Switching (MPLS) technique, i.e., setting up an LSP (Label Switched Path) along the service traffic path designated by the bearer control layer with a resource reservation method and setting up an end-to-end LSP using a display route mechanism of Resource Reservation Setup Protocol with Traffic-Engineering Extensions (RSVP-TE) or Constrain-based Routing LDP (CR-LDP).
In the above method, end-to-end topology structures and resources status of the whole network should be known first so as to provide a strict guarantee for the end-to-end QoS. However, in the viewpoint of commerce and security, an independent operating network may not hope that any other independent operating network knows its local disposition and quality status of the network resources. So the application of the method is limited.
Currently, there are many other Diff-Serv models with an independent bearer control layer, such as a Bandwidth-agent model of a serving Quality-of-Service backbone (Qbone). FIG. 2 is a map of a Bandwidth-agent model of a serving Qbone. As shown in FIG. 2, the model sets up a corresponding bandwidth agent for each Diff-Serv administration domain such as bandwidth agents 1, 2 and 3. The bandwidth agent is in charge of dealing with bandwidth application requests from users' hosts, servers, or network maintenance personnel, and determining whether to ratify a user's bandwidth application according to the current resource reservation status, policies configured, and a Service Level Agreement (SLA) that a user has subscribed to. The internal structure of this bandwidth agent is shown in FIG. 3, including: an inter-domain interface, a user service interface, a policy interface, an interface of network management, a route information database, a database, an intra-domain interface, and a simple policy service module. This bandwidth agent records various static or dynamic information including configuration information of various kinds of SLAs, physical network topology information, configuration and policy information of routers, user authentication information, current resource reservation information, and information of network occupation status. Meanwhile, the bandwidth agent also records route information to determine the user's service traffic path and the location of a cross-domain downstream bandwidth agent. The Diff-Serv administration domains herein refer to administration domains A, B, and C shown in FIG. 2.
In this technical scheme, a bandwidth agent directly manages the routers' resources and configuration information in its administration domain, which may have problems of over complicated topology and management; meanwhile, as the bandwidth agent needs to record the dynamic route information of the local domain, there may also exist a problem that route tables have to be updated too frequently, which may lead to unstable network resource reservation Besides, it may be difficult to keep the service route determined by the bandwidth agent according to the dynamic route information of the local domain identical with the actual transmitting route of the service traffic.